Aster is a stoic young Cardian Master who was considered a genious amongst his peers and fought against the invasion of Cataclysm. While he survived it and the energy wars that followed, his school did not. When the final invasion came and devastated his home beyond repair, he took to the stars in a quest for revenge.

Aster travels the the Milky Way hunting down remnants of the Cataclysm Forces and exterminating them. During his travels he meets Amarylla, whom he quickly realises is Sailor Meida, and reluctantly allows her to join his quest.